In U.S. Pat. No. 3,595,786 granted on Jul. 27, 1971 to Horvath et al. for an apparatus for treating fluids, a feeder device is disclosed which includes a dissolution chamber having a liquid/wastewater/water inlet and an outlet. The wastewater passing through the dissolution chamber contacts chemical treating agents in the form of tablets stacked within cylinders having lateral openings exposing lowermost of the tablets to the wastewater. An adjustable weir is arranged down-stream of the tablet cylinders which creates a degree of damming of the wastewater within the dissolution chamber. The adjustable weir is designed to provide an adjustable height of the liquid level within the dissolution chamber at different flow rates of the wastewater to better concentrate and disperse the treating agent therethrough. At different flow rates the height of the liquid level in the dissolution chamber is obviously different, and it is highly desirable to create a proportional relationship between the flow rate of the wastewater and the amount of chemical treating agent which is dissolved therein.
In U.S. Pat. No. 4,759,907 granted on Jul. 26, 1988 to Kawolics et al., a feeder device for controlled dissolution of a solid treating agent in a liquid of variable flow rate is designed such that the concentration of treating agent in the effluent liquid or wastewater can be substantially constant, irrespective of the actual flow rate of the liquid. The consistency of the concentration of the agent is obtained by the provision of an upstream proportional weir positioned in connection with a dissolution chamber which maintains a liquid volume in the dissolution chamber which can be linearly proportional to the flow rate of the liquid therethrough. The weir can be fixed or can be adjustable for varying chemical concentration dependent upon liquid flow.
In U.S. Pat. No. 3,495,948 granted to Long et al. on Feb. 17, 1970, a bypass dissolver includes two main chambers, one receiving a larger, untreated flow portion and the other chamber receiving a minor flow portion wherein the chemical treating agent is dissolved during its passage in contact with a pervious magazine of treating agent. The bypass dissolver is designed such that the flow rate of the smaller stream portion, in which the treating agent is dissolved, remains constant irrespective of the flow rate of the larger stream portion or the total flow rate. Thus, the dissolution rate of the treating agent is constant over time, independent of the total flow rate.
In U.S. Pat. No. 3,746,170 granted to Bloom et al. on Jul. 17, 1973, a liquid-treating apparatus includes a tank wherein the liquid to be treated is kept at a constant level and containers with treating agent are immersed into the liquid at an adjustable immersion depth. Manual adjustment of these containers to control the immersion depth is required. A constant concentration of treating agent in the liquid passing through this apparatus may not be obtained therewith.
Other patents in the field of wastewater treatment include Jordan, U.S. Pat. No. 4,211,655 issued on Jul. 8, 1980; Held, U.S. Pat. No. 4,584,106 issued on Apr. 22, 1986; Junker et al., U.S. Pat. No. 5,089,127 issued on Feb. 18, 1992; Kidon et al., U.S. Pat. No. 4,117,560 issued on Oct. 3, 1978; Hoadley, U.S. Pat. No. 5,441,073 issued on Aug. 15, 1995; Drewery, U.S. Pat. No. 5,441,711 issued on Aug. 15, 1995; Elkin, U.S. Pat. No. 3,195,985 issued on Jul. 20, 1965; Harvey, U.S. Pat. No. 4,732,689 issued on Mar. 22, 1998; Hannibal, U.S. Pat. No. 2,649,203 issued on Aug. 18, 1953; and Tang, U.S. Pat. No. 5,405,540 issued on Apr. 11, 1995.
U.S. Pat. No. 4,338,191 issued on Jul. 6, 1982 to Jordan and U.S. Pat. No. 5,350,512 issued to Tang on Sep. 27, 1994 are particularly directed to chlorination and dechlorination systems for wastewater or other fluid in which a container formed of space chamber portions connected by cylindrical-like tubular sections in vertical alignment house therein cylindrical tubes for holding a supply of stacked chemical treating tablets which are fed in magazine fashion vertically downwardly so that as the tablets are dissolved at the bottom of the container due to the contact thereof with the liquid, the tablets automatically feed down by gravity. U.S. Pat. No. 4,338,191 specifically discloses cylindrical-like tubular sections between the vertically spaced chamber portions of the container for accurately guiding and locating the tablet dispensing holder members or tubes in their operative positions. This patent also discloses four such tablet feeders associated with a chamber and weirs for regulating the flow of wastewater therethrough.